Blackberry represents but one of the many plants attacked by Bacterium tumefaciens. The galls (Fig. 45) produced are very much like those on raspberry, except that at the crown they are often larger and frequently occur along the stem above ground. The blackberry suffers to a considerable extent from Crown Gall. The tree fruits, like the apple and pear, may at times outgrow the galls, but the bush fruits, such as the blackberry and raspberry, succumb more readily. It seems that the blackberry, like the peach, is more readily infected than some of the other fruits. Possibly this is explained on the grounds that bush fruits are set relatively close to each other, which feature of their culture is more conducive to inoculation and gall - formation.

(See more complete discussion under Apple, page 108. See also Raspberry, page 398.)

Fig. 45.   Crown Gall disease on blackberry canes.

Fig. 45. - Crown Gall disease on blackberry canes.